This invention relates to a single-stage process for the production of xcex1-hydroxy ethers by oxidation of Cxe2x95x90C unsaturated compounds with hydroperoxides in the presence of a mono- or polyhydric alcohol as a nucleophile and solvent, wherein systems based on molybdenum compounds with boron trifluoride or alumina or 1,8-diazabicyclo-[5.4.0]-undec-7-ene or 1,4-diazabicyclo-[2.2.2]-octane are used as catalysts.
Industry has an interest in xcex1-hydroxy ethers, for example those represented by formulae (I) and (II). The compounds according to formula (I) may be employed in cosmetics, as lubricants for synthetic resins, in emulsion paints, as solvents, and as surfactants or co-surfactants.
The compounds according to formula (II) belong to the group of gemini surfactants, such as those described in WO 96/16033. These compounds according to formula (II) either serve as precursors of the ionic and nonionic, amphiphilic compounds referred to in WO 96/16033, or may be used as emulsifiers, demulsifiers, auxiliaries in metal working, ore mining, or surface finishing, as textile auxiliaries, or for cleaning and washing textiles or hard surfaces, and for washing and cleaning skin and hair. 
R1, R2, R4, and R6, independently of one another, are saturated, unbranched or branched hydrocarbon radicals, or are completely or partially fluorinated hydrocarbon radicals having 1 to 22 carbon atoms, preferably 8 to 18 carbon atoms. In detail, the radicals methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, n-eicosyl, n-henicosyl, n-docosyl, and the branched-chain isomers thereof or their completely or partially fluorinated hydrocarbon radicals are referred to herein.
R3 represents mono- or polyhydric, linear or branched radicals of alcohols having 1 to 22 carbon atoms which may also be fluorinated wholly or in part. Examples include methanol, ethanol, n- and iso-propanol, n- and iso-butanol, pentanol, hexanol, heptanol, n-octanol, 2-ethyl hexanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, heneicosanol, docosanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, trimethylol propane, neopentyl glycol, glycerol, and trifluoroethanol and mixtures thereof. Among long-chain alcohols, particularly those compounds with even carbon numbers are preferred. R5 is a spacer consisting of an unbranched or branched chain with 2 to 100 carbon atoms which contains 0 to 20 oxygen atoms, 0 to 20 nitrogen atoms, 0 to 4 sulfur atoms, and 0 to 3 phosphorus atoms, and which has 0 to 20 functional side groups, such as hydroxyl, carbonyl, carboxyl, amino and/or acylamino groups. Said spacer is described in greater detail in WO 96/16033 incorporated by reference herein.
X and Y, independently of one another, are substituents according to formula XVI
xe2x80x94(C2H4O)xcex1(C3H6O)xcex2Hxe2x80x83xe2x80x83(XVI)
where
xcex1=0 to 50, preferably xcex1=10 to 30,
xcex2=0 to 60, preferably xcex2=20 to 40,
and
xcex1+xcex2=1 to 100, preferably
xcex1+xcex2=10 to 50,
and wherein the alkoxide units are incorporated randomly or blockwise and the sequence is optional,
or are substituents according to formula XVII
xe2x80x94(C2H4O)xcex3(C3H6O)xcex4xe2x80x94FRxe2x80x83xe2x80x83(XVII)
where each
xcex3=0 to 20, preferably xcex3=0 to 8,
xcex4=0 to 20, preferably xcex4=0 to 12,
and
xcex3+xcex4=0 to 40, preferably
xcex3+xcex4=5 to 20,
and FR represents a functional radical
xe2x80x94CH2xe2x80x94COOM, xe2x80x94SO3M, xe2x80x94P(O(OM)2,
xe2x80x94C3H6xe2x80x94SO3M, or
xe2x80x94Oxe2x80x94C(O)xe2x80x94C2H3(SO3M)xe2x80x94CO2Mxe2x80x2,
wherein M, Mxe2x80x2 are equal to alkali, ammonium, alkanol ammonium, or xc2xd alkaline earth metal.
In each case the degree of alkoxylation is a mean which, within the defined limits, can be any value, including a non-integral one.
Prior-art processes for the production of said hydroxy ethers from olefins comprise two stages. At first, the olefin is epoxidized with a suitable oxidant and then purified. Per-acids are employed as oxidants for the epoxidation of long-chain olefins. Using silver catalysts, ethylene and butadiene can directly be reacted with oxygen to yield the corresponding epoxides. The customary method for producing propylene oxide is by molybdenum-, vanadium-, or titanium-catalyzed epoxidation of propylene with hydroperoxides. Although it is well known from literature that long-chain epoxides, too, can be epoxidized by the so-called Halcon (or oxirane) process [for example, cf. R. A. Sheldon, J. Mol. Catal., 7 (1980), 107], said process has not been employed hitherto for this purpose. In the second stage of the process for producing xcex1-hydroxy ethers the epoxides are opened with an alcohol usually in the presence of a catalyst. Since epoxides are rather expensive, they are rarely utilized for industrial processes. Thus, there remained a pressing need for a process which does not require expensive raw materials and wherein the epoxide stage occurs as an intermediate stage.
The opening of the oxirane ring is fairly easy with short-chain epoxides, such as ethylene oxide or propylene oxide, but requires ever-severer reaction conditions with increasing chain lengths. Both acids and bases are suitable as catalysts. In practice, classical Bronsted acids, such as H2SO4 [see R. A. Wohl, Chimie, 28 (1974) 1; DE 38 29 735], a large number of different Lewis acids [see e.g. P. Gassmann, T. Guggenheim, J. Am. Chem. Soc., 104 (1982) 5849; M. Bischoff, U. Zeidler, H. Baumann, Fette, Seifen, Anstrichmittel, 79 (1979) 131], heteropolyacids [see e.g. Y. Izumi, K. Hayashi, Chem. Lett. (1980) 787], and Al2O3 [cf. G. H. Posner, Angew. Chem., 90 (1978) 527] as well as sulfuric acid-treated phyllosilicates [cf. S. Hellbardt, K. Schlandt, W. H. Zech, DE 42 03 077] have been employed. However, the latter ones require significantly higher temperatures ( greater than 130xc2x0 C.).
There are only few experiments known from literature which describe the production of xcex1-hydroxy ethers from olefins by a single-stage synthesis. U.S. patent specification 2,808,442 describes the wolfram-catalyzed direct synthesis of xcex1-hydroxy ethers by reaction with a 35% to 100% hydrogen peroxide. The water which is inevitably present results in the formation of vicinal diols. Therefore, when using a 35% hydrogen peroxide, the xcex1-hydroxy ethers are defined as mere by-products. Titanium silicalites, too, have been used as catalysts for the direct synthesis of xcex1-hydroxy ethers from olefins and alcohols using hydrogen peroxide (cf. GB 2 252 556), but the problem of competing ring opening due to the presence of water persists.
Hence, it is the object of the present invention to develop a process for the direct, single-stage production of xcex1-hydroxy ethers which process is carried out in the absence of water, thus preventing the competing production of diol which is regarded as the main disadvantage of the processes described hereinabove.
According to the present invention, the problem is solved by using
organic hydroperoxides, ROOH, as oxidants
homogeneous or heterogeneous molybdenum compounds as a first catalyst component
boron trifluoride in the form of a stabilized complex, or an alumina, or 1,8-diazabicyclo-[5.4.0]-undec-7-ene, or 1,4-diazabicyclo-[2.2.2]-octane as a second catalyst component
mono- or polyhydric alcohols as nucleophiles and, simultaneously, as solvents without precluding the use of other solvents.
Therefore, the subject matter of the present invention is a single-stage process for the production of xcex1-hydroxy ethers according to formulae (I) and (II) which process is performed by the oxidation of olefinic substrates with organic hydroperoxides and opening of the resultant oxirane ring using mono- or polyhydric alcohols, characterized in that molybdenum compounds in combination with boron trifluoride or alumina or 1,8-diazabicyclo-[5.4.0]-undec-7-ene or 1,4-diazabicyclo-[2.2.2]-octane are employed as a catalyst system.
Examples of alumina, Al2O3, particularly include xcex1-Al2O3 (corundum), xcex3-Al2O3, or hydrates, such as xcex1-Al2O3.H2O (diaspore), xcex3-Al2O3 (boehmite), Al2O3.3H2O (hydrargillite), or Al2O3.3H2O (bayerite).
Although each of the reaction components is known, it is surprising that they can be combined in a single-stage process wherein the reaction selectively yields the xcex1-hydroxy ether. The catalyst components do not have any adverse effects on each other. On the contrary, it has been found that BF3 enhances the activity of the molybdenum catalyst for epoxidation.
According to the process of the present invention, suitable catalyst components for the epoxidation are molybdenum compounds which are either soluble in the reaction mixture, e.g. molybdenyl acetylacetonate, MoO2(acac)2, or molybdenum hexacarbonyl, Mo(CO)6, or molybdenum oxide on a support as a heterogeneous catalyst. Suitable catalyst supports are amorphous alumino-silicates or zeolites with high Lewis acidity. The molybdenum catalyst is employed in quantities of 0.01 to 5 mole %, preferably 0.25 to 2 mole %, most preferably 0.5 to 1.0 mole %, relative to the Cxe2x95x90C double bond to be oxidized.
Boron trifluoride or adducts, such as etherate or methanolate, may be employed as the second catalyst component according to the instant invention. Further examples include alumina, Al2O3, the basic compound 1,8-diazabicyclo-[5.4.0]-undec-7-ene, and 1,4-diazabicyclo-[2.2.2]-octane which are used in quantities of 0.01 to 5 mole %, preferably 0.25 to 2.0 mole %, most preferably 0.5 to 1.0 mole %, based on the Cxe2x95x90C double bond to be oxidized.
Suitable olefinic substrates are terminal and/or internal, singly or multiply unsaturated aliphatic, cyclic, or acyclic hydrocarbons, such as di- and trimers of butene or tri- and tetramers of propene, or unsaturated fatty acids and the esters thereof. Expediently, the alcohol component of the fatty acid esters should be identical with the alcohol employed in order that the likewise catalyzed transesterification does not result in undesirable product mixtures.
Mono- or polyhydric alcohols with primary, secondary, or tertiary hydroxyl groups and optional chain lengths may be used in the process of the present invention. For the production of compounds according to formula (II) it is desirable to use only primary hydroxyl groups for the etherification so that undesirable product mixtures are avoided. The alcohol and the olefinic substrate may contain additional functional groups, such as ester groups, carbonyl carbons, amides, ethers, provided that these groups do not interfere as nucleophiles during the reaction.
Suitable oxidants for the process of the present invention are commercially available hydroperoxides, such as tert-butyl hydroperoxide or cumene hydroperoxide, which are employed in proportions of 1.0 to 1.3, based on the double bond equivalents to be oxidized.
The reaction according to the process of the present invention can be carried out at any temperature ranging from the melting point to the boiling point of the reaction mixture. For safety reasons, a temperature of 100xc2x0 C. should not be exceeded. Furthermore, the reaction is carried out in an inert gas atmosphere and with dehydrated reactants. The reaction is initiated by mixing catalyst components and alcohol plus olefin and heating this mixture to reaction temperature. Then, the hydroperoxide is slowly added. Once the reaction is terminated, the catalyst components can be filtered off and further utilized if both are heterogeneous, which is the simplest case, or they have to be eliminated from the product by means of water. The xcex1-hydroxy ethers thus produced can be purified by distillation if desired.
The present invention will now be described with reference to the following non-limiting examples.